Sugar OK for making yeast starter?

I want to start a batch of beer off this weekend but it's a kit with just a small dried yeast pack so I'm thinking it might be better to make a starter. The thing is, I have no wort and don't want to open the kit itself till I'm ready to start fermenting.

Is there any reason why I couldn't just use sugar to make the starter? If so, what would I do? I'm thinking:

Boil a pint of water with maybe 50 grams of sugar for 10 mins, transfer to a sanitised bottle and cool the syrup by putting the bottle in cold water, then, around 20deg.C pitch the dried yeast in, and leave to breed for a day before using it to pitch the wort.

Also, do I need to get an airlock for the starter or are there any simple tricks to avoid this (such as clingfilm and an elastic band) as it would be a 70km round trip to get one.

You generally don't need to make a starter when using dry yeast since the cell-count is much higher than liquid. If you were going to make one, it's a bad idea to use sugar as this will train the yeast to eat the wrong stuff off the bat and they may produce off-flavors when you get them doing their thing in actual wort.

Counterintuitive as it may seem, dry yeast packets contain more yeast cells than liquid vials. I've never needed to make a starter with dry, and never had a particularly slow fermentation start (usually within twelve hours).

Cheyco's right about the sugar, too. I've also heard it explained that when you grow yeast in a simple sugar solution, the cells that are more apt to do well and reproduce are those that happen to be best at using simple sugars - not the maltose that ultimately needs to be consumed. You're in effect encouraging the wrong yeast to develop.

Sugar also has no nutrients, so the yeast will be weak. You would be much better off opening your kit if it has some extract in it. You can use dark molasses.

You don't need an airlock on a starter, just a cover.

No need to make a starter for dried yeast. In fact it can be detrimental and against the manufacturers recommendations. It contains a nutrient and will of used it by the time you pitch it.

The only time you'd really need consider it is if you where making a really big beer or one witha High ABV.

Just pitch it from the pack or maybe rehydrate it before pitching.

I always just rehydrate my dry yeast for 20 mins or so in lukewarm (boiled and cooled) water. Usually get a start withing 4-12 hours.